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Biomedical subjects

G Bereziat

Publications and source records attributed to G Bereziat.

12 recordsLinked to original sources
PubMed1979

[Biliary lithiasis in cystic fibrosis. Study of the bile salts in the serum and in the bile in one case (author's transl)].

Biliary lithiasis was discovered in a girl aged 11 suffering from Cystic Fibrosis and who underwent partial small bowel resection for meconium ileus. A cholecystectomy was performed at 15. Examination of the stones showed that they were composed of cholesterol and chemical examination of the bile showed an increase of phospholipids and a decrease in bile salts. There was also a modification of the ratio (Formula: see text) in the serum and the bile. All those factors contribute to the insolubility of cholesterol and to the formation of lithiasis. For all those reasons, the authors recommend a regular radiologic surveillance of the gallbladder in Cystic Fibrosis.

Adolescent↗
PubMed1979

Phospholipase activities in subcellular fractions of human platelets.

A homogenate of human platelets was fractionated by zonal ultracentrifugation into membranes, various granules and mitochondria. The membrane fraction was composed of two populations. The first, which represented 75% of the proteins, was rich in plasma membranes; the second, which represented the remaining 25%, was rich in microsomal membranes. Lysophospholipase was essentially localised in the cytosol. Phospholipase A1 which was only weakly bound to membranes, was mostly found in the soluble fraction (75%); the remainder was located in the plasma membranes and the mitochondria. Two-thirds of the phospholipase A2 was found in the particulate fractions.

Adult↗
PubMed1978

Studies on a new variant of the Hermansky-Pudlak syndrome: qualitative, ultrastructural, and functional abnormalities of the platelet-dense bodies associated with a phospholipase A defect.

The structure and functions of platelets from a patient in whom albinism and hemorrhagic diathesis were associated have been investigated. Electron microscope studies showed a large reduction in the number of dense bodies and this was confirmed by an examination of fluorescent platelets loaded with mepacrine. The rare dense bodies were much bigger than normally observed; their density was diminished and was localized in a peripheral ring. Other platelet constituents were found to be normal. Platelet peroxidase activity was normal in the canaliculi of the dense tubular system; catalase-positive granules were also present. Serotonin uptake by the patient's platelets was much decreased and reserpine, a potent inhibitor of serotonin accumulation by normal human platelets, did not further decrease this incorporation. The uptake of free 14 C-arachidonic acid by the platelets was greatly diminished, as was its thrombin-induced liberation from phosphatidyl-choline and phosphatidyl inositol. Moreover, platelet phospholipase A1 activity was much reduced and phospholipase A2 activity was undetectable.

Adult↗
PubMed1978

Phospholipases of plasmic membranes of adipose tissue. Possible intermediaries for insulin action.

In the present investigation we have shown that cytoplasmic membranes of adipocytes contain A1 and A2 phospholipase activities which are optimal in a buffer with 5 mM Ca2+ (pH 8.5). Insulin enhances these activities within phosphatidylethanolamine. Insulin increases also the amount of free fatty acids in membranes. Rodbell and Blecher have already shown an insulin-like action of phospholipases towards the uptake of glucose and amino-acids by adipocytes. Shier and Asakawa have recently described that lysolecithin and unsaturated fatty acids can change nucleotide-cyclase activities of cytoplasmic membranes towards GTP and ATP; lysolecithins and Triton X 100 seem to react in an identical way. Results from these studies give new suggestions on insulin action; phospholipase activation changes membrane physiochemical properties inducing an increase of glucose carrier mobility and leading the membrane cyclase enzyme (s) towards GMP cyclic synthesis.

Adipose Tissue↗
PubMed1977

[Platelets fatty acid variation in patients with atherosclerosis (author's transl)].

Plasma linoleic acid levels were found to be low in the atherosclerosis patients investigated. In contrast, platelet arachidonic acid levels were decreased only when atherosclerosis was combined with diabetes or mixed hyperlipidemia. In acute vascular thrombosis, a marked decrease in platelet arachidonic levels occurrrd, irrespective of whether the patient had atherosclerosis or not.

Arachidonic Acids↗
PubMed1977

[Plasma bile acids fractionnation by gas-liquid chromatography : application to hepatocellular deficiency investigation (author's transl)].

The level of the four major bile acids was measured in the plasma using gas liquid chromatography. The enhancement of the level of the primary bile acids was well known during bile duct obstruction. In the case of hepatic diseases, the chenodesoxycholiccholic acid concentration ratio (CDC/C) was equal or lower than unity when cholestasis occurred rather than hepatic deficiency. When hepatic deficiency developed, the ratio CDC/C was higher than unity. Plasma bile acid fractionnation exhibits also a prognostic value. When the ratio CDC/C is very high, it is significant of progressive hepatic deficiency. A high level of lithocholic acid is also a sign of unfavourable prognosis.

Bile Acids and Salts↗
PubMed1975

[Subcellular localization of rat adipocyte lipoprotein lipase].

The sub-cellular localisation in rat fat cells of lipoprotein lipase is discussed in this paper. The lipoprotein lipase was found with maximum activity in the microsomal fraction. Some special features of this activity in membrane fraction are pointed out.

Adipose Tissue↗
PubMed1975

[Rat liver plasma membrane phospholipase A].

The plasma membranes phospholipase A2 studied in situ shows very little sensitivity for pH variations ; the optimal concentration for Ca++ is 5 mM ; the enzymatic kinetics are of the Michaelis type. An inactive state of the phospholipase A2 exists : when rats are injected with heparin, their plasma membranes contain a very low phospholipase A2 activity. These membranes recover a high A2 activity if they are incubated in the presence of a rat platelets lysate. Treatment of membranes by NaCl 1 M displaces phospholipase A1 and phospholipase A2 but for the latter only when being in active state. Treatment of animals, conditions of preparation and of incubation of membranes influence the respective amounts of phospholipases A1 and A2 present in these membranes and are discussed in this paper. The localisation of these enzymatic proteins inside the membrane according to the membranous model proposed by Singer et al. [18] is also discussed.

Animals↗